Wired broadcast distribution



15a 1931. E. E. CLEMENT 1,336,904

WIRED BROADCAST DI STRIBUT ION Filed y 18, 1926 2 Sheets-Sheet l E. E CLEMENT WIRED BROADCAST DISTRIBUTION bea ls, 1931.

Filed y 18, 1926 2 Sheets-Sheet 2 Patented Dec. 15, 1931 OFFICE EDWARD E. cnnmzr, '1 wns nirq ron, pI's'rRIc'r or coLuMBIA, ASSIGNOR ro EDWARD F. COLLADAY; OF WASHINGTON; DISTRICT or COLUMBIA wines immerse I'irsiriaiisiirxon Application men may 18,

invention relates to broadcast distribution over line wires to subscribers sta-' tions. Ithas for its object the improvement of suchdistribution in divers particulars as hereinafter appears. Stated generally, the 1nven't1dncontemplates the use of multiplex amplifying and transmitting means at the central distributing pifice, which will send out current of identical frequency but displaced in phase over different conductors, which may be wires or any equivalent media; and the provision at a receiving stale tion of an instrument which will respond to the current in displaced phases, while un- 1 afiected by ordinary currents transmitted over the circuits.

My invention is illustrated in the V pan 'ing drawings, in which V Fig. 1 is a diagram showing a duplex at range'ment of tubes at a central e'flice' for am plifying and transmitting cl'lrrents' ever wire circuits to a substation. p

, Figs. 2, 3', 4, 5, 6,7, and s are respectively diagrams of modifications in the receiving apparatus.

Referring to the drawings, 1 and 2 repre sent a pair of metallic circuit line wires extending from a central station G to a sub scribers station S 9nd fOI" the sake Of @0111 pleteness being assumed to represent a tele phone line having terminal apparatus J at the central office and a sub'scribers telephone T at the substation. Bridged across the line at the central station aretwo vacuum tubes VV, having their plate circuits pp connected to the line wires 1 2 respectively. The grid circuits are connected by a common coupler to' the circuit 3' ter urinating in the switch m by which it may be connected either to a local metallic circuit or to a relay circuit 33. The relay N' is supposed to receive broadcast matter; either by radiation, or by carrier current, or by other means, and to demodulate or otherwise reduce the same to audio frequencies which are impressed on the circuit 3. If it be desired to receive and transmitthro ugh tubes VV' carrier current or superaudio freuencies modulated this will necessitate are acumen or a detector or (racemes at the amplifier (if any suitable type. This same arrangement of receiving tubes V V may be employed for receiving audio frequency waves over the line, in which case the tubes will act as amplifiers, Without other change from the showing of Fig. 8.

both Figs. 1 and 8 the usual A and Bf batteries are provided for the filament and plate circuits of the tubes VVV At the subscribers station as shown in Fig. 1 an" electromagnetic receiver R is shown provided with a pair of choke coils oh and a pair of electromagnetic operating coils r.o" supposed to produce polar changes in a suitable magnetic circuit acting upon the diaphragm or other sound producing agency (l. The choke coils may be wound to supplement each other for the metallic circuit, and to balance or neutralize each other in effect for the simplex circuit composed of the two wires 1' 2 and the ground 1. The receiver coils r% r" are wound to very high resistance, which is rendered possible first by the high resistance of the plate circuits of the tubes VV,' and second by the voltage of the B battery which would have in such an ampliher a voltage of the order of 90 or 100, or more. As the current in such a circuit is very small, the" present arrangement gives a number of advantages: first, the resistance of the line wires is halved; second, the current rises i-Ii' one wire as it falls in the other, hence the inductive effect on other wires or pairs in a cable is negligible; third, the effect of the undillations in opposite phase in the two plate circuits is cumulative in the receiver R assuming the coils r-r to be properly wounde supplement each other in efiect on the diaphragm. The imposition of the tubes V ,'V and the receiver R on the line has no 'fiect upon the telephone use of the line, because of the very high ohmic resistance involved as well as the choking eflect of the coils oh; and finally the telephone currents in the metallic circuit will have no effect upon the receiver R, and while the telephone T is in a bridge of the simplex circuit, the adjustment of the electromagnetic constants in the circuit may be made such as to prevent any substantial leakage of the broadcast current through the telephone receiver, even though the latter be off the hook during broadcast receiving. A slight leakage of this is not detrimental, because it serves to remind telephone users that radio receiving is going on; and it can be prevented entirely by properly relating the telephone bridge to the bridge of the receiver R, which is contemplated by but forms no specific part of the present invention.

Fig. 2 shows the coils 0h0h wound on a ring core in proper direction to neutralize each other for the simplex circuit and supplement each other for the metallic circuit, to prevent short circuiting the telephone.

Fig. 3 shows another method of winding the coil 071. on separate cores, the receiver in this case being a loud speaker connected to the simplex circuit through a transformer 251". The primary windings of this transformer rr function the same as in the receiver R in Fig. 1, but should be so related to the secondary windings that the undulations in the secondary circuit are cumulative.

Fig. 4'.- shows an arrangement similar to Fig. 3 but with the coils r acting directly on the diaphragm d.

Fig. 5 shows a modification in which the coils chch are wound upon a common 'core. These windings are supposed to be of low ohmic resistance but in series producing high inductance and in parallel neutralizing each other for any electromagnetic effect, while coils 1? have a very high resistance of the order of several thousand ohms each.

Fig. 6 shows another modification wound on a closed core, in which each of the windings 0k is doubled on itself, being preferably formed of two wires wound together on the core and then connected as shown. The oint ends 56 are connected by a wire 7, the ends 89 are connected to the line wires 12 respectively, and the ends 1011 go to the coils rr or their equivalent. This same circuit is schematically shown in Fig. 7, with the cores indicated as separate. Currents in the simplex circuit pass from the two line wires to ground through the double windings ch in series, so that each double winding neutralizes itself so far as any effect on the core is concerned, but the effect of the currents passing in the coils 1"r is maximum. Currents from the metallic circuit on the other hand would pass from wire 8 through one-half of the winding of the first coil ch to the point 5, then through the wire 7 to the point 6 and through one-half of the second winding 0b to wire 9. This affords a maximum of impedance between the wires 89, with only ohmic resistance of the coils which is low in the grounded circuits.

It is to be understood that numerous changes and modifications may be made in the circuits thus described without departing from the principles of this invention which is presented herein as one embodiment only of principles which are applicable to many forms of circuits and apparatus. It is possible with this arrangement to convey enough energy over the two conductors of the metallic circuitto operate a loud speaker at the subscribers station without any local amplification. It is also possible to operate the simplex circuit as shown, without any inductive effect on any other circuit in the same cable. Various other benefits will occur to those skilled in the art as well as the possibility of modifications referred to, which are intended to be included herein insofar as they fall within the scope of the appended claims.

What I claim is:

1. A transmitting station, a receiving station, a two-wire metallic circuit extending between them, means for producing a current flow in said metallic circuit as such, means at the transmitting station for producing current impulses in the two wires of the metallic circuit in parallel, as a phantom circuit, with phases displaced, together with a receiver at the receiving station and means to recompose the displaced phases and cause the same to supplement each other and to act cumulatively upon said receiver, said transmitting station being a service station, said receiving station being a subscribers station, the flow of current in the metallic circuit being in response to regular service requirements, and the flow of current in the phantom circuit being in response to special service requirements, the regular service instruments being irresponsive to the special service current, and the special service instruments being irresponsive to the regular service current.

2. A system comprising a plurality of metallic circuits, as described in claim 1, each with independent means to transmit and receive signals over the metallic circuit, and each having an individual phantom connection to propagate desired undulations in the two sides of the metallic circuit in parallel, with means to displace the phases thereof, whereby disturbing inductive effects on other circuits are avoided.

3. A system as described in claim 1, in which the transmitting station is a central ized service station, with a plurality of receiving stations and a plurality of metallic circuits extending from the service station thereto individually, a duplex vacuum tube relay for each circuit at the service station,

means for transmitting signals over the metallic circuit and means to receive the same, means to supply special signals to said vacuum tube relays and to cause the same to impress undulations corresponding thereto on the two sides of a metallic circuit in parallel and With their phases displaced, together with means at each subscribers station adapted to receive and recompose said dephased undulations, and a receiver responsive thereto.

4. A combined service system, a special signaling system comprising a centralized servive station, subscribers stations, and individual metallic circuits interconnecting said subscribers stations and said service station, means for signaling to and from a subscribers station over his metallic circuit,

means at the service station for producing signaling currents of special service character, a duplex relay for each metallic circuit, having its input terminals connected to receive said special service signals, and having its output terminals connected to the tWo sides of the metallic circuit, a receiver at each subscribers station and means to receive and properly relate the special service signaling currents to produce cumulative effects upon said receiver, said last named means and said receiver being irresponsive to the regular service currents in the metallic circuit.

In testimony whereof I hereunto afiix my signature.

EDWARD E. CLEMENT. 

